gun·sel \ˈgən(t)səl\noun (-s) Etymology: probably from Yiddish genzel gosling, from Middle High German gensel, diminutive of gans goose, from Old High German — more at goose 1.slang: a young, naïve, or stupid person 2.slang: a treacherous person 3.slang: catamite 4.[influenced in meaning by gun (I) ]slang: gunman